Noise-isolated rocker arm cover

ABSTRACT

A rocker arm cover has a circumferential flange bonded to an underlying elastomeric pad. The pad is further bonded to an underlying channel member having a gasket disposed therein. Circumferentially disposed cap screws extend through the channel member and gasket to removably attach the integrated cover assembly to the head or block of an internal combustion engine.

Umted States Patent 1191 1111 3,773,142

Bragg et al. [4 1 Nov. 20, 1973 [54] NOISE-ISOLATED ROCKER ARM COVER 2,981,247 4/1961 Gaebler 123 9038 [75] Inventors: Gary 0. Bragg, Dunlap; Nelson A.

Jones Peoria, both f 11 Primary Examiner-Richard B. Wilkinson Assistant Examiner-Vit W. Miska [73] Ass1gnee: Caterpillar Tractor Co., Peoria, Ill. An0mey paul Lempio [22] Filed: Oct. 2, 1972 21 Appl. No.: 294,255 1 71 ABSTRACT A rocker arm cover has a circumferential flange 52 US. Cl. 181/33 K, 123/9038, 123/198 E bonded to an underlying elaswmeric p The p is 51 1111. C1. E04b 1 99, GlOk 11/04 further bonded to an underlying channel member [58] Field of Search 181/33 K; 123/198 E, ing a gasket disposed therein- Cirwmferemially 123/90 38 posed cap screws extend through the channel member and gasket to removably attach the integrated cover 5 References m assembly to the head or block of an internal combus- UNITED STATES PATENTS engme' 3,090,463 5/ 1963 Yanda 181/33 K 12 Claims, 1 Drawing Figure PMENIEDuuvzo 1975 3,773,142

NOISE-ISOLATED ROCKER ARM COVER BACKGROUND OF THE INVENTION Internal combustion engines transmit an appreciable amount of vibrational energy to engine mounted components during engine operation. Since the human ear is highly sensitive to a frequency range of from 800Hz to 3,000Hz, many attempts have been made to isolate or absorb such energy prior to its transmittal to rocker arm covers and the like. For example, British Patent No. 1,218,734 discloses an annular gasket disposed between split portions of a rocker arm cover to attempt to attenuate noise resulting therefrom.

SUMMARY OF THE INVENTION An object of this invention is to provide a cover assembly attached to an engine for substantially isolating vibrational energy during engine operation. The cover assembly comprises a cover having a peripheral flange formed therearound, an underlying elastomeric pad, exhibiting high vibrational energy loss properties, bonded to the flange, an underlying rigid member bonded to the pad and an elastomeric gasket compressed between the member and the engine to form a static seal thereat.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a transverse, cross sectional view of a noise-isolated rocker arm assembly attached to an engine.

DETAILED DESCRIPTION The drawing illustrates a rocker arm cover assembly removably attached to the cylinder head or block of an internal combustion engine 11. The cover assembly completely encloses the rocker arms and attendant mechanisms (not shown) to protect them against damage and to prevent the egress of lubricating oil therefrom. A cover, which may constitute die-cast aluminum or the like, comprises vertical sidewalls 12 and a top wall 13. The top wall preferably forms an inverted V- shape to define a longitudinally extending ridge 14 on the cover assembly.

A peripheral flange 15 extends transversely from the sidewalls and circumvents the cover assembly. An elastomeric pad means 16, exhibiting high vibrational energy absorption and loss properties, underlies and is bonded to the flange by a suitable bonding agent. The plastic or rubber pad means may comprise a continuous strip of elastomeric material, such as 40 to 60 durometer nitrile rubber having a thickness of from oneeighth to one-fourth of. an inch.

The elastomeric properties of the pad means are preferably tailored to provide a spring rate for tuning the natural frequency of the isolated cover away from the natural exciting frequency emanating from the moving parts of the engine. In addition, the amplitude of the cover vibrations will be dampened by absorbing vibrational energy in the hysteresis of the pad means, resulting in enhanced damping and minimal noise transmittal.

A rigid member 17 underlies and is bonded to the pad means by a suitable bonding agent. The member preferably comprises an inverted U-shaped channel having vertically disposed-and parallel inner and outer legs 18 and 19, respectively, defining a. continuous channel 20 having a continuous elastomeric gasket 21 disposed therein. A plurality of attaching means, such as cap screws 22, project through the member and the gasket for compressing the gasket to form a static seal thereat completely around the cover assembly.

Cut-outs 23 are formed through flange 15 and pad means 16 to accommodate the head of each cap screw therein. The predetermined degree of compression imparted to the gasket by the cap screws is precisely achieved by stop means comprising the extremities of legs 18 and 19 which are drawn into abutting engagement with a top planar surface 24 of the engine.

Although the above cover assembly is particularly useful for rocker arm cover applications, it should be understood that the teachings herein can be likewise applied to timing gear covers, oil pans and the like.

What is claimed is:

1. An engine having a noise suppressing cover assembly attached thereto, said cover assembly comprising a cover having a peripheral flange formed therearound,

elastomeric pad means having high vibrational energy loss properties underlying and bonded to said flange,

a rigid member underlying and bonded to said pad means,

an elastomeric gasket disposed between said member and said engine, and

releasable attaching means, attaching said cover assembly to said engine, projecting solely through said member and said gasket forcompressing said gasket to form a seal thereat which circumvents said cover.

2. The invention of claim 1 wherein said cover constitutes a rocker arm cover having said top .wall forming an inverted V-shape in transverse cross section to define a longitudinally extending ridge on said cover.

3. The invention of claim 2 wherein said member forms an inverted U-shape in cross section to comprise vertically disposed and parallel inner and outer legs dey fining a continuous channel therearound, said gasket disposed in said channel.

4. The invention of claim 3 wherein at least one of said legs abuts said engine to provide stop means for imparting a predetermined degree of compression to said gasket.

5. The invention of claim 1 wherein said attaching means each comprises a cap screw and further comprising means forming a cut-out through each of said flange and said pad means for accommodating the head of .each of .said cap screws.

6. The invention of, claim ,1 whereinsaid pad means constitutesa continuous strip having-a durometer hardness approximating about from forty to sixty.

7. A noise suppressing cover assembly comprising .a cover having a peripheral flange formed therearound,

elastomeric, noise isolating pad means having high vibrational energy loss properties underlying and bonded to said flange,.and

a rigid memberunderlying and bonded to said pad means,

said member formingan inverted U-shape cross section to comprise vertically disposed and parallel inner and outer legs defining a continuous channel therearound adapted to receive a gasket therein.

.8. The invention of claim 7 wherein said cover constitutes a rocker arm cover having said top wall forming an inverted V-shaped in transverse cross section to define a longitudinally extending ridge on said cover.

9. The invention of claim 7 wherein said member forms an inverted U-shape cross section to comprise vertically disposed and parallel inner and outer legs defining a continuous channel therearound adapted to receive a gasket therein.

10. The invention of claim 7 furhter comprising means forming a cut-out through each of said flange and said pad means for accommodating the head of an attaching means therein.

11. The invention of claim 8 wherein said pad means constitutes a continuous strip having a durometer hardness approximating about from forty to sixty.

12. An engine having a noise suppressing cover assembly attached thereto, said cover assembly comprising a cover having a peripheral flange formed theretherearound, said gasket disposed in said channel. 

1. An engine having a noise suppressing cover assembly attached thereto, said cover assembly comprising a cover having a peripheral flange formed therearound, elastomeric pad means having high vibrational energy loss properties underlying and bonded to said flange, a rigid member underlying and bonded to said pad means, an elastomeric gasket disposed between said member and said engine, and releasable attaching means, attaching said cover assembly to said engine, projecting solely through said member and said gasket for compressing said gasket to form a seal thereat which circumvents said cover.
 2. The invention of claim 1 wherein said cover constitutes a rocker arm cover having said top wall forming an inverted V-shape in transverse cross section to define a longitudinally extending ridge on said cover.
 3. The invention of claim 2 wherein said member forms an inverted U-shape in cross section to comprise vertically disposed and parallel inner and outer legs defining a continuous channel therearound, said gasket disposed in said channel.
 4. The invention of claim 3 wherein at least one of said legs abuts said engine to provide stop means for imparting a predetermined degree of compression to said gasket.
 5. The invention of claim 1 wherein said attaching means each comprises a cap screw and further comprising means forming a cut-out through each of said flange and said pad means for accommodating the head of each of said cap screws.
 6. The invention of claim 1 wherein said pad means constitutes a continuous strip having a durometer hardness approximating about from forty to sixty.
 7. A noise suppressing cover assembly comprising a cover having a peripheral flange formed therearound, elastomeric, noise isolating pad means having high vibrational energy loss properties underlying and bonded to said flange, and a rigid member underlying and bonded to said pad means, said member forming an inverted U-shape cross section to comprise vertically disposed and parallel inner and outer legs defining a continuous channel therearound adapted to receive a gasket therein.
 8. The invention of claim 7 wherein said cover constitutes a rocker arm cover having said top wall forming an inverted V-shaped in transverse cross section to define a longitudinally extending ridge on said cover.
 9. The invention of claim 7 wherein said member forms an inverted U-shape cross section to comprise vertically disposed and parallel inner and outer legs defining a continuous channel therearound adapted to receive a gasket therein.
 10. The invention of claim 7 furhter comprising means forming a cut-out through each of said flange and said pad means for accommodating the head of an attaching means therein.
 11. The invention of claim 8 wherein said pad means constitutes a continuous strip having a durometer hardness approximating about from forty to sixty.
 12. An engine having a noise suppressing cover assembly attached thereto, said cover assembly comprising a cover having a peripheral flange formed therearound, elastomeric pad means having high vibrational energy loss properties underlying and bonded to said flange, a rigid member underlying and bonded to said pad means, en elAstomeric gasket disposed between said member and said engine, and releasable attaching means, attaching said cover assembly to said engine, solely projecting through said member and said gasket for compressing said gasket to form a seal thereat which circumvents said cover, said member forming an inverted U-shape in cross section to comprise vertically disposed and parallel inner and outer legs defining a continuous channel therearound, said gasket disposed in said channel. 